Analytical Synthesis and Simulation-Based Kinematic Analysis of a Crank–Rocker Mechanism for Cutter bar Drives

Abstract

Aims: To synthesise the dimensions of a crank–rocker mechanism for driving the cutter bar of a crop harvesting machine using Freudenstein's equation, evaluate the kinematic characteristics of the mechanism, and validate the analytical results through SolidWorks Motion Analysis. Study Design: The study involved an engineering design approach combined with analytical kinematic analysis and computer-based simulation to validate the developed mechanism. Place and Duration of Study: Department of Farm Machinery and Power Engineering, Kelappaji College of Agricultural Engineering and Food Technology, Tavanur, Malappuram, Kerala Agricultural University, from January 2026 to March                    2026. Methodology: A four-bar crank–rocker mechanism was designed to generate the reciprocating motion required to achieve a 76.2 mm stroke of the cutter bar using Freudenstein's equation. The synthesised linkage was subsequently checked using Grashof's criterion to ensure continuous rotation of the input crank, and the kinematic behaviour of the mechanism was analysed. A three-dimensional model of the mechanism was then developed in SolidWorks, and Motion Analysis was performed. The kinematic results from analytical calculations and simulation were compared for validation. Results: The synthesised linkage satisfied Grashof's criterion, confirming that the selected mechanism could operate as a crank–rocker mechanism with continuous rotation of the input crank. The analytical model predicted a cutter-bar stroke of 74.68 mm, whereas the SolidWorks Motion Analysis produced a stroke of 75.89 mm. The difference between the two values was 1.21 mm. The maximum cutter-bar velocity obtained analytically was 2.92 m/s, compared with 2.64 m/s from the simulation. The maximum acceleration predicted by the analytical model was 207.68 m/s², while the corresponding simulated value was 206.48 m/s², with a difference of only 0.58%. The transmission angle varied from 48.81° to 66.75° during one complete revolution of the crank, indicating suitable transmission of motion and force from the coupler to the rocker throughout the operating cycle. Conclusion: The close agreement between the analytical and SolidWorks simulation results confirms the validity of the developed kinematic model for the crank–rocker cutter-bar mechanism. The results demonstrate that the proposed mechanism is suitable for driving the cutter bar of a crop harvesting machine and provide a useful basis for further dynamic analysis and prototype development.